1、mysqli_connect ([ string $host
= ini_get("mysqli.default_host") [, string $username
= ini_get("mysqli.default_user") [, string $passwd
= ini_get("mysqli.default_pw") [, string $dbname
= "" [, int $port
= ini_get("mysqli.default_port") [, string $socket
= ini_get("mysqli.default_socket") ]]]]]] ) : mysqli
参数:主机,用户名,密码,数据库,端口号
返回一个对象,代表当前连接的MySQL服务器
$link = mysqli_connect("127.0.0.1", "my_user", "my_password", "my_db");
if (!$link) {
echo "Error: Unable to connect to MySQL." . PHP_EOL;
echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;
echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;
exit;
}
echo "Success: A proper connection to MySQL was made! The my_db database is great." . PHP_EOL;
echo "Host information: " . mysqli_get_host_info($link) . PHP_EOL;
mysqli_close($link);
/*
Success: A proper connection to MySQL was made! The my_db database is great.
Host information: localhost via TCP/IP
*/
2、mysqli_query ( mysqli $link
, string $query
[, int $resultmode
= MYSQLI_STORE_RESULT ] ) : mixed
对数据库执行一次查询
参数1:由mysqli_connect() 或 mysqli_init() 返回的链接标识。
失败时返回 FALSE
,通过mysqli_query() 成功执行SELECT, SHOW, DESCRIBE或 EXPLAIN查询会返回一个mysqli_result 对象,其他查询则返回TRUE
。
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
/* Select queries return a resultset */
if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
printf("Select returned %d rows.\n", mysqli_num_rows($result));
/* free result set */
mysqli_free_result($result);
}
mysqli_close($link);
3、mysqli_real_escape_string ( mysqli $link
, string $escapestr
) : string
此函数用来对字符串中的特殊字符进行转义, 以使得这个字符串是一个合法的 SQL 语句。 传入的字符串会根据当前连接的字符集进行转义,得到一个编码后的合法的 SQL 语句。
在调用 mysqli_real_escape_string() 函数之前, 必须先通过调用 mysqli_set_charset() 函数或者在 MySQL 服务器端设置字符集。
参数1:由mysqli_connect() 或 mysqli_init() 返回的链接标识。
参数2:需要进行转义的字符串。会被进行转义的字符包括: NUL (ASCII 0),\n,\r,\,'," 和 Control-Z.
返回值:转义后的字符串。
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
/* 检查连接 */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City");
$city = "'s Hertogenbosch";
/* 由于未对 $city 进行转义,此次查询会失败 */
if (!mysqli_query($link, "INSERT into myCity (Name) VALUES ('$city')")) {
printf("Error: %s\n", mysqli_sqlstate($link));
}
$city = mysqli_real_escape_string($link, $city);
/* 对 $city 进行转义之后,查询可以正常执行 */
if (mysqli_query($link, "INSERT into myCity (Name) VALUES ('$city')")) {
printf("%d Row inserted.\n", mysqli_affected_rows($link));
}
mysqli_close($link);
/*
Error: 42000
1 Row inserted.
*/